This invention relates to an improved chemical oxidation method for treating waste water containing organic particles by which the particles are disinfected or stabilized and are separated from the water. More particularly, this invention relates to improvements in the chemical oxidation process and apparatus of the general types disclosed in U.S. Pat. No. 3,943,955 issued Mar. 16, 1976 to Bradley and U.S. Pat. No. 3,953,331 issued Apr. 27, 1976 to Bradley. The process disclosed in these two prior patents refer generally to, and are stated to be improvements upon, a chemical oxidation process disclosed in an earlier U.S. Pat. No. 3,300,402 issued Jan. 24, 1967 to Grich and Hood. The processes disclosed in these prior patents are directed towards the treatment of waste water, that is, waste material containing organic waste particles suspended in water, such as sewage, septage waste, sludges produced by municipal treatment plants, food preparation or food processing wastes, and the like. The objective is to disinfect or stabilize the solid particles into a substantially water-free sludge.
In the waste water treatment process disclosed in the foregoing U.S. Pat. Nos. 3,943,955 and 3,953,331, the waste material, which is soupy in texture, is thoroughly mixed with chlorine gas in a primary reactor tank or chamber. The reaction in the chamber, which takes place at a predetermined pressure, oxidizes the organic materials. The treated solid particle-containing water material which flows from the chamber is divided into two parts. One part (e.g. 75-85%) is returned to the primary reactor along with fresh, untreated waste material for re-treatment while the remaining part (e.g. 15-25%) is treated in a secondary reactor. The treatment in the secondary reactor involves swirling the waste material within a tank or chamber to continue the reaction under pressure. The pressure in the secondary reactor is about the same or a slightly lower than that found in the primary reactor. The treated material flowing from the secondary reactor is then removed and dewatered.
The dewatering of the treated waste material typically involves pouring the material into a lagoon or pond and allowing the solid particles to settle to the bottom. Then the water, which is above the sludge formed by the coalesced particles, is removed by pumping, evaporation or the like conventional water removal techniques. This dewatering system requires a substantial lagoon area and a considerable amount of time. For example, it may take thirty to sixty days to complete the settlement of the particles, at which time the water may be removed. In a typical municipal type of treatment plant, where waste water material is continuously processed, the lagoon facilities must be extensive to handle the quantity of waste water treated.
Prior chemical oxidation waste water treatment facilities have operated on a continuous basis, that is, continuously receiving waste water and continuously treating the waste water until the water is deposited in the available lagoon for settlement. Since chemical oxidation is adapted to handle large quantities of waste water within relatively short periods of time per gallon of waste water, such systems potentially have considerable advantage over other waste water treatment systems which utilize aerobic, anaerobic or both types of treatments. However, the chemical oxidation treatment, such as that described in the above-mentioned patents to Bradley, U.S. Pat. Nos. 3,943,955 and 3,953,331, may produce noxious odors during operation which, at times, are intolerable to the surrounding area and require shutdown of the facilities until dissipation. In addition, although the chemical oxidation system equipment can be relatively compact, because of the extensive settling lagoons that are required for dewatering, a considerable amount of area is needed for such a treatment facility.
Thus, the present invention is concerned with two major areas of improvements over the prior chemical oxidation process. One improvement area concerns the elimination of the noxious odor problem while simultaneously producing a sludge which is consistently and uniformly more stabilized or disinfected than the sludge of the prior process. The second area of improvement is concerned with rapidly dewatering, that is, separating the sludge from the water, so as to eliminate the need for extensive lagoons or any other types of dewatering systems that are presently used for dewatering waste sludges.